Quiz - Physics - Volume/Pressure

[saxman242]

If you included the word "noticible" in the question, things become very clear.

Expansion of the tank and increase of the pressure inside are equally noticeable. They both require outside instrumentation to be added.

 

[ToneNQ]

It's physics it either happens or doesn't, whether it can be seen by the eye is irrelevant, it can be measured. .............

It's physics, this inarguably happens, but it's measurement is relative. Dive physics and physiology that are immeasurable to the diver are quite relevant to our dive plan. For the purposes of an OW lesson, what is the piece of knowledge that needs to be retained?

We inflate balloons with lung pressure, which is about 0.1Bar max. Any pressure change will be less than that.

You could prove one answer with an SPG and a ruler. The other answer might be able to measure the tank change-in-circumference, but you'll need a 1000Pa pressure differential gauge for the balloon.

 

[Steve_C]

When we have our tanks hydroed my understanding is that the tank is put in a water bath, a pressure is applied, and the expansion of the tank is measured by the rise in water level. Too much expansion, too weak a tank wall. So tank expansion is a measurable thing. Of course we should have our tanks at a lower pressure.

 

[Storker]

tank expansion is a measurable thing.

Depends on your tolerances.

Sometimes, I only need a yardstick. Sometimes, I need a caliper. Sometimes, I need a micrometer. If you can measure it with a micrometer, it's measurable. That doesn't mean you will see a noticeable difference if your tolerance requirement is in the yardstick range and you're using the appropriate measuring tool

 

[saxman242]

Depends on your tolerances.

Sometimes, I only need a yardstick. Sometimes, I need a caliper. Sometimes, I need a micrometer. If you can measure it with a micrometer, it's measurable. That doesn't mean you will see a noticeable difference if your tolerance requirement is in the yardstick range and you're using the appropriate measuring tool

That's just a matter of technique. Wrap a string around the tank a handful of times and you can measure tank expansion with a yard stick.